U.S. patent application number 11/546026 was filed with the patent office on 2008-04-10 for printing device structures using nanoparticles.
This patent application is currently assigned to Nokia Corporation. Invention is credited to Toni Ostergard.
Application Number | 20080083926 11/546026 |
Document ID | / |
Family ID | 39274353 |
Filed Date | 2008-04-10 |
United States Patent
Application |
20080083926 |
Kind Code |
A1 |
Ostergard; Toni |
April 10, 2008 |
Printing device structures using nanoparticles
Abstract
The specification and drawings present a new apparatus and
method for printing transistor or diode structures using
nanoparticles (e.g., silicon nanoparticles). Si-based electronic
structures (e.g., transistors, diodes) can be printed in a simple
low cost process and thus being a potential alternative to obtain a
low cost manufacturing process for, e.g., Si-based active matrix
(AM) backplanes as well as other applications.
Inventors: |
Ostergard; Toni; (Turku,
FI) |
Correspondence
Address: |
WARE FRESSOLA VAN DER SLUYS & ADOLPHSON, LLP
BRADFORD GREEN, BUILDING 5, 755 MAIN STREET, P O BOX 224
MONROE
CT
06468
US
|
Assignee: |
Nokia Corporation
|
Family ID: |
39274353 |
Appl. No.: |
11/546026 |
Filed: |
October 10, 2006 |
Current U.S.
Class: |
257/64 ;
257/E21.114; 257/E21.382; 257/E29.182; 257/E29.187; 257/E29.255;
438/149; 438/478; 977/773; 977/887 |
Current CPC
Class: |
H01L 29/735 20130101;
H01L 29/78 20130101; H01L 29/66325 20130101; H01L 21/02601
20130101; H01L 29/7317 20130101; H01L 29/0673 20130101; B82Y 10/00
20130101; H01L 21/02628 20130101; H01L 21/02532 20130101; H01L
29/0665 20130101 |
Class at
Publication: |
257/64 ; 977/773;
977/887; 438/149; 438/478 |
International
Class: |
H01L 29/06 20060101
H01L029/06; H01L 21/36 20060101 H01L021/36 |
Claims
1. An apparatus, comprising: a substrate; and at least one
transistor or diode structure disposed on said substrate, wherein
said at least one transistor or diode structure comprises: at least
one semiconductor region comprising nanoparticles doped with p or n
impurities and disposed using printing.
2. The apparatus of claim 1, wherein said at least one transistor
or said diode structure comprises at least one further
semiconductor region comprising undoped nanoparticles.
3. The apparatus of claim 1, wherein said nanoparticles are silicon
nanoparticles.
4. The apparatus of claim 3, wherein said silicon nanoparticles
have a size in a range of one to one hundred nanometers.
5. The apparatus of claim 1, wherein said at least one
semiconductor region has a predetermined level of doped n or p
impurities.
6. The apparatus of claim 1, wherein said at least one transistor
or diode structure is a bipolar transistor and the at least one
semiconductor region comprises three semiconductor regions with
nanoparticles forming pn junctions, each said semiconductor region
having a different concentration of said n or p impurities and
disposed using said printing.
7. The apparatus of claim 1, wherein substrate is made of one of:
a) a dielectric material, and b) a plastic material.
8. The apparatus of claim 1, wherein said at least one transistor
or diode structure is a metal-oxide-semiconductor field-effect
transistor or a pn junction diode.
9. The apparatus of claim 1, wherein, before said disposing, said
nanoparticles are formed and a solution is formed with said
nanoparticles, and said printing is performed using said solution
comprising said nanoparticles.
10. The apparatus of claim 1, wherein said printing is one of: a)
an ink-jet printing, and b) an ink-jet printing, wherein an ink-jet
printer system/ink head is combined with an ultra sound
generator.
11. The apparatus of claim 1, further comprising at least one
electrode made of a conducting material for making an electrical
contact with said at least one semiconductor region, wherein said
at least one electrode is disposed on: a) said at least one
semiconductor region after said at least one semiconductor region
is printed, and b) on said substrate before said at least one
semiconductor region is printed.
12. The apparatus of claim 1, wherein, after disposing, said at
least one semiconductor region is thermally annealed for improving
a connection between said nanoparticles.
13. The apparatus of claim 11, wherein, before said annealing, said
at least one semiconductor region is surface-activated by a metal
for reducing a temperature for annealing.
14. The apparatus of claim 1, wherein said at least one
semiconductor region is further filled with a filler material for
improving a connection between said nanoparticles.
15. The apparatus of claim 13, wherein said filler material is a
conducting material, a semiconducting organic material or a
polymer.
16. The apparatus of claim 1, wherein all components of said at
least one transistor or diode structure are disposed on said
substrate using said printing.
17. The apparatus of claim 1, wherein said at least one transistor
or diode structure is a part of an active matrix backplane of a
liquid crystal display.
18. A method, comprising: disposing at least one transistor or
diode structure on a substrate, wherein said at least one
transistor or diode structure comprises: at least one semiconductor
region comprising nanoparticles doped with p or n impurities and
disposed using a printing technique.
19. The method of claim 18, wherein said at least one transistor or
said diode structure comprises at least one further semiconductor
region comprising undoped nanoparticles.
20. The method of claim 18, wherein said nanoparticles are silicon
nanoparticles.
21. The method of claim 18, wherein said at least one transistor or
diode structure is a bipolar transistor and the at least one
semiconductor region comprises three semiconductor regions with
nanoparticles forming pn junctions, each said semiconductor region
having a different concentration of said n or p impurities and
disposed using said printing.
22. The method of claim 18, wherein said at least one transistor or
diode structure is a metal-oxide-semiconductor field-effect
transistor or a pn junction diode.
23. The method of claim 18, wherein, before said disposing, said
nanoparticles are formed and a solution is formed with said
nanoparticles, and said printing is performed using said solution
comprising said nanoparticles.
24. The method of claim 18, wherein, after disposing, said at least
one semiconductor region is thermally annealed for improving a
connection between said nanoparticles.
25. An electronic device, comprising: a) a module comprising: a
substrate; and at least one transistor or diode structure disposed
on said substrate, wherein said at least one transistor or diode
structure comprises: at least one semiconductor region comprising
nanoparticles doped with p or n impurities and disposed using a
printing technique; and b) a component comprising said module.
26. The electronic device of claim 25, wherein said component is a
liquid crystal display and said module is an active matrix
backplane of said liquid crystal display.
27. The electronic device of claim 25, wherein said at least one
transistor or said diode structure comprises at least one further
semiconductor region comprising undoped nanoparticles.
28. The electronic device of claim 25, wherein said nanoparticles
are silicon nanoparticles.
29. The electronic device of claim 25, wherein said at least one
transistor or diode structure is a bipolar transistor and the at
least one semiconductor region comprises three semiconductor
regions with nanoparticles forming pn junctions, each said
semiconductor region having a different concentration of said n or
p impurities and disposed using said printing.
30. The electronic device of 25, wherein said at least one
transistor or diode structure is a metal-oxide-semiconductor
field-effect transistor or a pn junction diode.
31. The electronic device of claim 25, wherein, before said
disposing, said nanoparticles are formed and a solution is formed
with said nanoparticles, and said printing is performed using said
solution comprising said nanoparticles.
32. An apparatus, comprising: means for depositing; and at least
one means for an electronic conversion disposed on said substrate,
wherein said at least means for an electronic conversion comprises:
at least one semiconductor region comprising nanoparticles doped
with p or n impurities disposed using a printing technique.
33. The apparatus of claim 32, wherein said means for depositing is
a substrate and said at least one means for an electronic
conversion is at least one transistor or diode structure
Description
TECHNICAL FIELD
[0001] The present invention relates generally to electronic
devices and, more specifically, to printing transistor or diode
structures using nanoparticles (e.g., Si nanoparticles).
BACKGROUND ART
[0002] One of the commonly used display technologies e.g. in mobile
devices today is active-matrix (AM) Liquid Crystal Display (LCD)
technology. The technology is also used in laptops, personal
computer monitors, televisions, etc. The technology is well known,
and the pixel driving in the displays is "based" on the well known
silicon (Si) transistor structure based, e.g., on a-Si, Low
Temperature PolySilicon (LTPS), Continuous-Grain Silicon (CGS),
etc.
[0003] However, the manufacturing costs of the active matrix (AM)
backplanes (i.e., the substrate with the transistor structures and
conducting lines) for displays may be relatively expensive.
Furthermore, the processing parameters related to the formation Si
transistors onto the substrate by processing of the deposited Si
thin film and thin-film transistor (TFT) structures may not be
optimal for certain substrates such as polymer (plastic) based
substrates. AM-backplanes can be manufactured onto plastic
substrates, but the manufacturing process is very challenging, and
additional cost may be the penalty (still in a research phase). The
use of plastic based substrates may have several benefits, such as
more durable displays, flexible/bendable/conformable displays
providing more design freedom, which are all driving the
development of plastic based LCDs.
[0004] Considering the cost issues of the AM-backplane
manufacturing, as well as the compatibility issue with plastic
based substrates, it is natural that researchers have been looking
for alternative solutions to obtain AM-backplanes. One approach
that has extensively been investigated is the use of organic based
semiconductors, i.e., conjugated molecules and polymers with
semiconducting properties. Such organic semiconducting materials
are well known and various types of materials are used, e.g., in
Organic Light Emitting Diodes/Displays (OLED) but also in Organic
Transistors such as organic TFTs (OTFTs) and organic field effect
transistors (OFETs). Recently, these organic transistors have been
seen as a potential alternative to Si in AM-backplanes.
[0005] The organic transistors are still in the research phase, but
some researchers and companies expect the technology to provide
significant benefits compared to Si in a long run, especially in
relatively simple applications such as AM-backplanes. The main
reason why organic transistors are extremely promising is the ease
of manufacturing that the use of organic semiconductors can
provide. Since the organic materials can be solution processed, it
is expected that the transistors can be printed, e.g. by ink-jet
printing, onto basically any substrate in a simple and low cost
manufacturing process.
[0006] Printing of organic transistors has already been extensively
demonstrated, e.g., in active matrix backplanes for flexible
displays (see, e.g., Polymer Vision: http://www.polymervision.com/,
downloaded Sep. 7, 2006), and mass-manufacturing processes are
currently being developed.
[0007] Although the performance of printed organic transistors may
not be able to compete with the best Si-transistors, the simple
manufacturing technique is expected to bring such huge benefits
that the technology will eventually be capable of replacing Si in
certain applications. One such application is expected to be the AM
backplane used for displays. The processing of Si into transistors
is simply expected to be too expensive compared to the simple
printing of organic transistors (in certain applications).
[0008] However, the conclusion that Si-based AM-backplanes will not
be competitive in the long run is based on the assumption that
Si-transistors cannot be printed in a similar simple fashion as
organic transistors, which so far has also been the case.
DISCLOSURE OF THE INVENTION
[0009] According to a first aspect of the invention, an apparatus,
comprises: a substrate; and at least one transistor or diode
structure disposed on the substrate, wherein the at least one
transistor or diode structure comprises: at least one semiconductor
region comprising nanoparticles doped with p or n impurities and
disposed using printing.
[0010] According further to the first aspect of the invention, the
at least one transistor or the diode structure may comprise at
least one further semiconductor region comprising undoped
nanoparticles.
[0011] According further to the first aspect of the invention, the
nanoparticles may be silicon nanoparticles. Further, the silicon
nanoparticles may have a size in a range of one to one hundred
nanometers.
[0012] Still further according to the first aspect of the
invention, the at least one semiconductor region may have a
predetermined level of doped n or p impurities.
[0013] According further to the first aspect of the invention, the
at least one transistor or diode structure may be a bipolar
transistor and the at least one semiconductor region may comprise
three semiconductor regions with nanoparticles forming pn
junctions, each the semiconductor region having a different
concentration of the n or p impurities and disposed using the
printing.
[0014] According still further to the first aspect of the
invention, the substrate may be made of one of: a) a dielectric
material, and b) a plastic material.
[0015] According still further to the first aspect of the
invention, the at least one transistor or diode structure may be a
metal-oxide-semiconductor field-effect transistor or a pn junction
diode.
[0016] According yet further still to the first aspect of the
invention, before the disposing, the nanoparticles may be formed
and a solution may be formed with the nanoparticles, and the
printing may be performed using the solution comprising the
nanoparticles.
[0017] Yet still further according to the first aspect of the
invention, the printing may be one of: a) an ink-jet printing, and
b) an ink-jet printing, wherein an ink-jet printer system/ink head
is combined with an ultra sound generator.
[0018] Still yet further according to the first aspect of the
invention, the apparatus may comprise at least one electrode made
of a conducting material for making an electrical contact with the
at least one semiconductor region, wherein the at least one
electrode may be disposed on: a) the at least one semiconductor
region after the at least one semiconductor region is printed, and
b) on the substrate before the at least one semiconductor region is
printed.
[0019] Still further still according to the first aspect of the
invention, after disposing, the at least one semiconductor region
may be thermally annealed for improving a connection between the
nanoparticles. Further, before the annealing, the at least one
semiconductor region may be surface-activated by a metal for
reducing a temperature for annealing.
[0020] According further still to the first aspect of the
invention, the at least one semiconductor region may be further
filled with a filler material for improving a connection between
the nanoparticles. Further, the filler material may be a conducting
material, a semiconducting organic material or a polymer.
[0021] According yet further still to the first aspect of the
invention, all components of the at least one transistor or diode
structure may be disposed on the substrate using the printing.
[0022] According still yet further to the first aspect of the
invention, the at least one transistor or diode structure may be a
part of an active matrix backplane of a liquid crystal display.
[0023] According to a second aspect of the invention, a method,
comprises: disposing at least one transistor or diode structure on
a substrate, wherein the at least one transistor or diode structure
comprises: at least one semiconductor region comprising
nanoparticles doped with p or n impurities and disposed using a
printing technique.
[0024] According further to the second aspect of the invention, the
at least one transistor or the diode structure may comprise at
least one further semiconductor region comprising undoped
nanoparticles.
[0025] Further according to the second aspect of the invention, the
nanoparticles may be silicon nanoparticles.
[0026] Still further according to the second aspect of the
invention, the at least one transistor or diode structure may be a
bipolar transistor and the at least one semiconductor region may
comprise three semiconductor regions with nanoparticles forming pn
junctions, each the semiconductor region having a different
concentration of the n or p impurities and disposed using the
printing.
[0027] According further to the second aspect of the invention, the
at least one transistor or diode structure may be a
metal-oxide-semiconductor field-effect transistor or a pn junction
diode.
[0028] According still further to the second aspect of the
invention, before the disposing, the nanoparticles may be formed
and a solution may be formed with the nanoparticles, and the
printing may be performed using the solution comprising the
nanoparticles.
[0029] According further still to the second aspect of the
invention, after disposing, the at least one semiconductor region
may be thermally annealed for improving a connection between the
nanoparticles.
[0030] According to a third aspect of the invention, an electronic
device, comprises: a) a module comprising: a substrate; and at
least one transistor or diode structure disposed on the substrate,
wherein the at least one transistor or diode structure comprises:
at least one semiconductor region comprising nanoparticles doped
with p or n impurities and disposed using a printing technique; and
b) a component comprising the module.
[0031] Further according to the third aspect of the invention, the
component may be a liquid crystal display and the module may be an
active matrix backplane of the liquid crystal display.
[0032] Still further according to the third aspect of the
invention, the at least one transistor or the diode structure may
comprise at least one further semiconductor region comprising
undoped nanoparticles.
[0033] According further to the third aspect of the invention, the
nanoparticles may be silicon nanoparticles.
[0034] According still further to the third aspect of the
invention, the at least one transistor or diode structure may be a
bipolar transistor and the at least one semiconductor region may
comprise three semiconductor regions with nanoparticles forming pn
junctions, each the semiconductor region having a different
concentration of the n or p impurities and disposed using the
printing.
[0035] According yet further still to the third aspect of the
invention, the at least one transistor or diode structure may be a
metal-oxide-semiconductor field-effect transistor or a pn junction
diode.
[0036] According further still to the third aspect of the
invention, before the disposing, the nanoparticles may be formed
and a solution may be formed with the nanoparticles, and the
printing may be performed using the solution comprising the
nanoparticles.
[0037] According to a fourth aspect of the invention, an apparatus,
comprises: means for depositing; and at least one means for an
electronic conversion disposed on the substrate, wherein the at
least means for an electronic conversion comprises: at least one
semiconductor region comprising nanoparticles doped with p or n
impurities disposed using a printing technique.
[0038] According further to the fourth aspect of the invention, the
means for depositing may be a substrate and the at least one means
for an electronic conversion may be at least one transistor or
diode structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] For a better understanding of the nature and objects of the
present invention, reference is made to the following detailed
description taken in conjunction with the following drawings, in
which:
[0040] FIGS. 1a and 1b are schematic representations (side and top
views, respectively) of a printed Si-based p-n-p bipolar transistor
with electrodes on top of a Si print, according to an embodiment of
the present invention;
[0041] FIG. 2 is a schematic representation (side view) of a
printed Si-based p-n-p bipolar transistor with electrodes under a
Si print, according to an embodiment of the present invention;
[0042] FIG. 3 is a flow chart for printing a transistor or diode
structure using nanoparticles (e.g., Si nanoparticles), according
to an embodiment of the present invention; and
[0043] FIG. 4 is a schematic representation of an electronic device
utilizing a component manufactured using printing transistor or
diode structures with nanoparticles (e.g., Si nanoparticles),
according to embodiments of the present invention.
MODES FOR CARRYING OUT THE INVENTION
[0044] A new method and apparatus are presented for printing
transistor or diode structures using nanoparticles (e.g., silicon
nanoparticles). According to embodiments of the present invention,
Si-based electronic structures (e.g., transistors, diodes) can be
printed in a simple low cost process and thus being a potential
alternative to obtain a low cost manufacturing process for, e.g.,
Si-based active matrix (AM) backplanes as well as other
applications such as processors requiring a very large-scale
integration (VLSI) level integration and performance.
[0045] According to an embodiment of the present invention, the
process can comprise:
[0046] Step 1: Formation of doped and un-doped nanoparticles (e.g.,
Si-nanoparticles);
[0047] Step 2: Formation of a solution with said nanoparticles;
and
[0048] Step 3: Printing of various transistor or diode structures
onto a substrate using solutions containing the Si-nanoparticles as
well as other relevant materials, and printing of other relevant
materials (e.g., conducting and insulating materials).
[0049] In step 1, the creation of nanoparticles (such as
Si-nanoparticles) can be done, e.g., by an electrochemical etching
of silicon wafers, as done by Professor Nayfeh's group at the
University of Illinois (e.g., see Akcakir et al, "Detection of
Luminescent Single Ultrsmall Silicon Nanoparticles Using
Fluctuation Correlation Spectroscopy", Applied Physics Letters, 76,
pp. 1857-1859 2000; Chaieb et al., "Assemblies of Silicon
Nanoparticles Roll up into Flexible Nanotubes", Applied Physics
Letters, 87, pp. 062104 2005).
[0050] Although Professor Nayfeh's group manufactures intrinsic
(undoped) Si-nanoparticles primarily for optical applications
(e.g., see Nayfeh M H, Rao S, Nayfeh O M, Smith A, and Therrien J,
"UV Photodectors with Thin-Film Si Nanoparticle Active Medium",
IEEE Transactions on Nanotechnology 4, pp. 660-668, 2005, and
Nayfeh O M, Rao S, Smith A, Therrien J, and Nayfeh, M H, "Thin Film
Silicon Nanoparticle UV Detectors", IEEE Photonics Technology
Letters 16, pp. 1927-1929, 2004), the manufacturing technique may
be extended to manufacturing of doped Si-nanoparticles as well, by
starting with a doped Si-wafer. Other techniques to obtain doped
and undoped Si-nanoparticles, such as mechanical grinding, can be
utilized as well.
[0051] Step 2: although individual atoms/molecules of pure silicon
may not be utilized for printing, extremely small particles of
silicon, i.e., nanoparticles (ranging from approximately 1 mm to
hundreds of nanometers, e.g., to one hundred nanometers) can be
dispersed into a suitable solvent and printed, e.g., with an
ink-jet printer. The use of ultrasound to obtain a dispersion of
nanoparticles is well known and equipment for obtaining such
dispersions is manufactured, e.g., by the company HIELSCHER (see
http://www.hielscher.com/ultrasonics/index.htm, downloaded Sep. 7,
2006). The method is well known, e.g., in the printing industry for
dispersing inks.
[0052] By combining an ultrasound disperser with an ink-jet
printing head, the dispersed Si-nanoparticles can be printed in a
simple printing process using a suitable solvent with an ultra
sound generator continuously mixing the solution in the solution
reservoir. However, other printing techniques such as Screen
printing (with a higher concentration of active material in the
"paste"), Gravure printing and others may be also used.
[0053] Step 3: by printing using the dispersed nanoparticles (e.g.,
Si-nanoparticles) with a suitable printing technique, one can
obtain various transistor and diode structures on practically any
substrate. In the case of an active matrix (AM) backplane for
displays, the structure of main interest is a transistor structure.
To obtain transistors (or other structures) suitable for the
AM-backplane one can use several different approaches demonstrated
in FIGS. 1a-1b and 2.
[0054] FIGS. 1a and 1b show an example among many others of
schematic representations (side and top views, respectively) of a
printed Si-based p-n-p bipolar transistor (which is a part of a
module 10) with electrodes 20, 22 and 24 on top of a silicon print,
according to an embodiment of the present invention. Here, in its
simplest form, the p-n-p bipolar transistor could be formed by
printing three parallel lines 14, 16 and 18 of p.sup.+, n, and p
doped Si, respectively, on a substrate 12. In addition to the three
printed lines 14, 16 and 18 of Si-nanoparticles, only the
conducting lines 20, 22 and 24 that are connected to the p.sup.+, n
and p regions, respectively, would be needed. The printing (e.g. by
ink-jet, screen printing, etc.) of such conducting lines is also
well known, e.g., by using an ink or a paste of a metal, carbon
particles, conducting polymers, etc. In the example of FIGS. 1a and
1b, the conducting lines 20, 22 and 24 are printed after printing
of the Si-nanoparticles lines 14, 16 and 18. FIG. 2 demonstrates
another example of a further embodiment, wherein the conducting
lines 20, 22 and 24 are printed first prior to the printing of the
Si-nanoparticles lines 14, 16 and 18. Also, a combination of both
approaches shown in FIGS. 1a-1b and FIG. 2 can be used, i.e., some
electrodes can be printed before printing the Si-nanoparticles
lines and other electrodes can be printed afterwards.
[0055] Thus, according to one embodiment of the present invention,
all components of the transistor or diode structure can be disposed
on the substrate using the printing technique.
[0056] Since devices made by printing nanoparticles (e.g.,
Si-nanoparticles) are based on the properties of Si and other
materials, all different structures that have been demonstrated in
these materials using the traditional lithography processes can be
also possible to manufacture using printing as the manufacturing
technique. Thus, other options to the bipolar transistor technology
would be the MOSFET (Metal-Oxide-Semiconductor Field Effect
Transistor) structures, either as NMOS(N-channel MOSFET), PMOS
(p-channel MOSFET) or CMOS (Complementary MOSFET). Other
alternatives may be (but are not limited to): pn junction diodes,
e.g., Thin Film Diodes (TFD), AM-backplane applications, etc.
[0057] The various structures of MOSFETs and Diodes are well known
to a person skilled in the art, and the structures (in their
various configurations) could be realized by using printable
nanoparticles (e.g., doped or undoped Si-nanoparticles), conducting
materials (e.g., metal, carbon particles or conducting polymers),
and various insulating materials (organic materials and/or
inorganic oxides, e.g., in a form of nanoparticles).
[0058] By using the printing method, according to embodiments
described herein, it is possible to print, e.g., Si-based
transistors, as well as other electronic elements/components.
However, the performance of said components may not be optimized
due to a limited contact area between the individual nanoparticles.
To improve the performance of the printed components two additional
approaches, thermal annealing (or annealing by radiation at
different wavelengths) and the use of an active "filler" material,
can be used.
[0059] The thermal annealing (or even crystallization) can be
performed by applying a direct heat, or by applying a laser light
of an appropriate wavelength (a similar process that is used for
obtaining low temperature poly silicon, LTPS). By annealing the
nanoparticle based material, the connection between the individual
nanoparticles and the device performance can be improved.
[0060] Furthermore, if the annealing temperature needs to be
lowered, it is also possible to use surface activated
Si-nanoparticles to reduce the energy required for the annealing
process. Such surface activated Si-nanoparticles could have, e.g.,
Ni, Al, or other suitable metals on their surface (e.g., by
electrochemically "attaching" metal atoms to the surface), i.e.,
said metals deposited as a separate layer that through diffusion at
elevated temperatures is incorporated into, and interacting with
the nanoparticles. Reducing the crystallization temperature in Si
by using various metals (e.g., in the form of NiSi.sub.2) is well
known to a person skilled in the art.
[0061] By using an active "filler" material, the connection between
the individual nanoparticles may also be improved. Such filler
materials could be conducting and/or semiconducting organic
molecules and/or polymers, and thus the approach would be more of a
hybrid approach between, e.g., traditional Si-transistors and
organic transistors (OTFTs). By blending the active "filler"
material(s) in suitable portions with the Si-nanoparticle solution,
the device performance may thus be improved. No thermal annealing
would be needed then, which could be highly desirable if plastic
based substrates are used. The printable "ink" would thus contain
the nanoparticles, the active "filler" and the solvent.
Furthermore, in line with the use of an active "filler" of, e.g., a
conjugated polymer/molecular material, the printed structures may
also be so called hybrid structures where some of the inorganic
materials are completely replaced with organic counterparts. For
example, in the transistor structures the insulating layer could be
based on an organic insulator such as PMMA (polymethyl
methacrylate) or its precursor, or another insulating polymeric
material.
[0062] FIG. 3 shows a flow chart for printing a transistor or diode
structure using nanoparticles (e.g., Si nanoparticels), according
to an embodiment of the present invention.
[0063] The flow chart of FIG. 3 only represents one possible
scenario among others. The order of steps shown in FIG. 3 is not
absolutely required, so generally, the various steps can be
performed out of order. In a method according to an embodiment of
the present invention, in a first step 30, doped and undoped (if
needed) semiconductor (e.g., Si) nanoparticles and possibly other
relevant materials are formed for all components of the transistor
or diode structure (including conduction lines, if appropriate). In
a next step 32, solutions with the prepared nanoparticles are
formed. In a next step 33, an active filler material (e.g.,
conducting material, a semiconducting organic material or a
polymer) is added to an appropriate solution intended for a
particular nanoparticle region. In a next step 34, a device
structure (e.g., transistor, diode, etc.) is printed on the
substrate using prepared solutions with semiconducting
nanoparticles (optionally with the active filler material), and
other relevant conducting and insulating components. Finally, in a
step 36, nanoparticle regions are thermally annealed optionally
using surface-activated metal (e.g., Ni, Al, in the form of NiSi2,
etc.) for improving connections between nanoparticles.
[0064] FIG. 4 shows an example of a schematic representation of an
electronic device utilizing a module 10, AM backplane, manufactured
using printing transistor or diode structures with nanoparticles
(e.g., Si nanoparticles), according to embodiments of the present
invention. The module 10 can be used in an electronic (e.g.,
portable or non-portable) device 100, such as a mobile phone, a
computer, a monitor, a TV set, personal digital assistant (PDA),
communicator, portable Internet appliance, digital video and still
camera, a computer game device, and other electronic devices
utilizing viewing. As shown in FIG. 4, the device 100 has a housing
210 to house a communication unit 212 for receiving and
transmitting information from and to an external device (not
shown). The device 100 also has a controlling and processing unit
214 for handling the received and transmitted information, and a
liquid crystal display module 230 for viewing. The module 230
includes an LCD display 192 and the AM backplane 10. The
controlling and processing unit 214 is operatively connected to the
AM backplane 10 to provide image data to the LCD display 192 to
display an image thereon.
[0065] It is to be understood that the above-described arrangements
are only illustrative of the application of the principles of the
present invention. Numerous modifications and alternative
arrangements may be devised by those skilled in the art without
departing from the scope of the present invention, and the appended
claims are intended to cover such modifications and
arrangements.
* * * * *
References